orchid soil

Potting Soil for Orchids – What Growing Medium For Your Plants?

Sharing is caring!

Name a houseplant and an orchid will definitely come on your list. With overwhelmingly more than 28,000 species across the globe except for Antarctica, the orchid is one of the oldest yet still modern widely grown plants in many gardens and indoor collections. 

You probably have noticed that many healthy and vibrant orchids do not grow in regular potting soil. The reason behind this is that general potting soil used in the majority of houseplants is too dense and compacted for their roots.

So do orchids need soil? What to plant orchids in? Interested to know what orchid soil you should use for your plants? 

Do not worry because this article will equip you with the basic knowledge in choosing the best orchid potting mix. 

Where can you originally find an orchid?

Orchids can be grouped into three depending on where and how they live. The most common are the epiphytes that are found growing on the bark of trees and shrubs. 

Next are the lithophytes that can thrive on hard rock surfaces. And last on the list is the terrestrials with over 200 species growing directly from the soil. 

The table below shows the distribution of popular species into these classifications:

Growth HabitOrchid plant
EpiphytesPhalaenopsis, Catasetum, Cattleya, Cycnoches, Encyclia, Vanda, Alamania, Aerides, Dendrobium, Bulbophyllum, Anguloa, Dendrochilum
LithophytesPhragmipedium, Bulbophyllum, Dendrobium, Paphiopedilums
TerrestrialErythodes, Macodes, Hetaeria, Zeuxine, Phaius, Liparis, Acanthephippium, Nervilia, Eulophia, Pachystoma, Bletilla, Calypso

How to Know If Your Orchid Is an Epiphyte, Lithophyte, or Terrestrial?

Different species of orchid plants certainly will require different potting mixes. Both epiphytes and lithophytes would prefer a mix that can provide more structural support and better drainage. 

Meanwhile, terrestrials fairly resemble a general house plant. If you do not know what kind of orchid you have, looking at the basic anatomy can probably give you some ideas. 

The parts of epiphytes and lithophytes are quite similar. They have thick and fleshy roots that can absorb moisture and some nutrients from the atmosphere. They also have succulent stems called pseudobulbs that are used to store water and help them survive during dry periods.

On the other hand, terrestrial orchids will commonly have below ground tubers and corms rather than pseudobulbs. The orchid roots also appear to be more extensive.

In fact, there are few species from the genus Rhizanthella that grow completely below the surface and only allow the flowers to rise above ground to be pollinated by insects.

A general potting mix for indoor plants can be used for terrestrial orchids.

Orchid Potting Soil Ingredients for Epiphytic and Lithophytic Types

Potting soil intended for these orchids contain at least one or a combination of both organic and inorganic materials. Because orchids are very diverse, the truth is there is no particular formula for orchid soil mix that will work for every plant.

Nonetheless, below is a list of planting materials and ‘orchid dirt’ that are deemed effective from one generation of growers to another.

Organic materials

Charcoal

The use of charcoal as a growing medium for orchids offers many benefits. It has antimicrobial properties and is best in eliminating nasty odor and salt buildup.

Wine cork

Cork barks are used by many to mount orchids. But did you know that corks from your red or white wine bottles could also work as a substrate? They can repel water and prevent the rotting of roots. The texture is also porous enough, especially if chipped, to provide anchorage.

Shredded wood bark

Since the majority of orchids are found thriving on tree trunks, wood barks will greatly resemble their natural habitat. Shredded barks are long-lasting and very chunky to use. They provide excellent aeration and stability for your plant.

Coconut husk chips

This is the go-to orchid potting substrate by many growers because of its affordability. It can retain water and nutrients while still giving the roots ample spaces to breathe.  

Sphagnum moss

The porosity of sphagnum moss (peat moss) is significantly high allowing better air circulation. It can also hold water and nutrients up to 20 times its weight. It is also acidic in nature which prevents diseases caused by fungi and bacteria. Ironically, the same properties are also blamed for the death of many orchids especially if left unchecked. 

Inorganic materials

Expanded clay aggregate

This material is lightweight and expands when soaked in water. The water that has been absorbed can provide moisture to the roots once needed. A clay ball also has lots of holes and it creates gaps for air to move. This will ensure that the roots can breathe.

Lava Rock

Lava rocks have good water retention and aeration properties. Because it is an organic rock, it will take time to break down and it can be reused anytime.

Perlite

Sold in almost all garden centers and shops, perlite both provides properties excellent for absorbing water and providing aeration. Although it will not give any nutrients to your plants.

Pumice

Similarly, pumice can provide the same properties perlite has. But the heavier weight of pumice provides better stability and anchorage for orchid plants. It is often mixed with shredded bark and moss.

Vermiculite

Vermiculite in combination with sphagnum moss is a great orchid growing medium. It can hold water well and gives enough space for root growth and air movement.

Rock wool

Rock wool is made from heating basalt and turning it into glass fibers. In between fibers of these cubes, it can hold water 5 times its weight. It also stays in shape preventing the risk of compaction. It can be mixed with expanding clay aggregates.

How to repot an orchid?

Step 1. Make sure to prepare all your materials. This includes your container or pot (size should be larger than before), sharp scissors, a large bucket, boiling water, and preferred potting mix.

Step 2. Sterilize your potting mix to avoid diseases or other problems that can be brought by the growing medium. Put the mix into a large bucket and soak it in boiling water. Once the temperature has gone down to room level, drain the water.

Step 3. Carefully pull the orchid from its current container. Try to loosen each root.

Step 4. Using a sharp scissor, remove any dead or rotten roots. If you wish to propagate, you can also divide it into clumps of pseudobulbs in this stage. Make sure you leave enough healthy roots per division.

Step 5. Orchids will remain unstable unless new roots have formed. Thus, considering its shoot-root ratio in positioning will make it more anchored in its new home. You can also use clips to hold the plant temporarily.

Step 6. Fill the orchid pots with the preferred potting mix. The general principle is that organic materials decompose more quickly than inorganic materials and would require more frequent repotting. 

Step 7. Water the plants just like how you did before. Give tender love and care and you will be surprised that it can live a century or more. What a lovely being that can grow old with you.

Fun facts about orchids

  • Orchids are found on every continent except for Antarctica. Scientists believed that they have been growing even before the continents geologically separated from each other.
  • The smallest orchid Platystele jungermannioides in the world is just about the size of a dime. It can be found in the cloud forests of Mexico, Guatemala, Panama, and Costa Rica.
  • The Tiger Orchid (Grammatophyllum speciosum) in Indonesia is the world’s tallest orchid with a height reaching up to 7.62 meters. The plant is native to Laos, Myanmar, Thailand, Philippines, Borneo, Vietnam, Indonesia, the Solomon Islands, and Papua New Guinea.
  • Only vanilla (Vanilla planifolia) is the commercially grown orchid crop for its essential oil.
  • Orchid seeds are so small that a single pod can contain up to 4,000,000 seeds.

I hope this guide gives you ideas about different types of potting medium and soil for orchids.

See more: What do orchids symbolize?

*image by Maridav/depositphotos

Scroll to Top